Is Soy Good for You?

- The Truth About Soy, Cancer, Estrogen and Moobs -

Is Soy Good for You?

The Truth About Soy, Cancer, Estrogen and Moobs



For most vegans and vegetarians, soy is a saving grace. From tofu to edamame and soy milk, this powerful plant is packed with protein, vitamins, and minerals to keep your meat-free body strong. But with its rise to popularity in recent years, soy has been subject to its own category of urban myth.

The source of the problem is one of soy’s most controversial ingredients: phytoestrogen. This natural plant hormone is estrogen-like, but is not estrogen. It is considered a SERM – a Selective Estrogen Receptor Modifier. It has the ability to act like estrogen, but can act the complete opposite, too. Confused yet? You aren’t alone. Luckily, we’re here to set the record straight and debunk the top three silly soy myths.

Myth #1: Soy is full of estrogen.


As we now know, soy contains phytoestrogen SERM, which is actually not estrogen at all. The most common type of phytoestrogens in soy are isoflavones. Although these plant-based compounds have the ability to attach themselves to estrogen receptors, they are also known to be picky little guys. They often won’t attach and sometimes they even have the opposite effect of estrogen on the body. [3][4]

Basically, phytoestrogens are sneaky. They’ve managed to convince people that they are estrogen and that soy products are chalk full of extra hormones that, in excess, could be harmful for the body.

Turns out the soy skeptics are looking in the wrong place. While soy products don’t contain any estrogen, animal products do. All female animals and some males naturally produce estrogen in their flesh, milk, and eggs, which is then transferred to the humans who consume it. Cow’s milk is especially high in estrogen and has been linked to cancer and reproductive disorders in men. [5]

So if you’re avoiding extra estrogen, tofu might actually be the way to go.

Myth #2: Soy can cause cancer.


Once again, this myth is linked to the belief that soy contains estrogen, which we know isn’t true. Since estrogen can increase the risk of certain cancers, it’s no surprise this rumour caught on. Here’s how it all started:

A few medical studies used lab rats to test the potential cancerous effects of soy. The rats that were injected with more isoflavones showed greater tumor growth overall. [6] Once released, these studies threw people into a soy tizzy.

What most people didn’t realize was that soy metabolizes differently in humans than in rodents. [6] There has been no medical proof of soy causing cancer in humans. The truth is, soy can actually reduce the risk of cancer.

The only proven link between soy and human cancer has been a positive one. Multiple studies have shown that isoflavones have anti-cancer effects, meaning that soy can greatly reduce the risk of getting cancer. [9] It’s been proven that women who consume soy can lower their risk of breast cancer recurrence by over 25%. [1] There’s even evidence that isoflavones can slow tumor spread and reduce prostate cancer in men. [2]

Whether you are battling cancer, fighting to make sure it doesn’t return, or finding ways to never fight it at all, soy could be a valuable weapon.

Myth #3: Soy will give men “moobs”.


This has to be our favourite of the soy myths. With all this talk of estrogen in soy, it’s no wonder some men believe they might develop if they have too much. Let’s debunk this myth right now: fellas, you can enjoy your soy without growing man boobs.

The medical term for “moobs” is gynecomastia and it’s a very real condition. However, there is no evidence that shows a causal connection between soy and gynecomastia. In fact, soy has no feminizing effects on the male body whatsoever. Since soy contains no estrogen, this makes perfect sense.

A 2010 study proved that, despite the results of rodent studies done before, isoflavones and soy products do not have any effect on testosterone levels in human men. The study also considered sperm count, infertility, and estrogen levels, but none of the above were impacted by soy. [5] One similar study even exhibited lower estrogen levels in men who consumed large amounts of soy. Essentially, soy made them even more manly than they were before. [7] All facts considered, it’s no surprise that vegan men have the highest testosterone levels. [8]

With all the confusion surrounding phytoestrogen and the impact of soy on lab rats, myths were bound to circulate. Thankfully, there is proof enough to debunk them. So go ahead – sauté that tofu and chug that soy milk. Your body might actually thank you in the long run.


By Sarah Johnson, Creative Writer at Upbeet Foods


Approved and endorsed by Dr. Tushar Mehta.



  1. Soy and Your Health – Physicians Committee for Responsible Medicine

  1. Insights Gained from 20 Years of Soy Research – The Journal of Nutrition

  1. Are Phytoestrogens Good or Bad for You? – Dr. Axe Food & Medicine

  1. Soy Isoflavones and Estrogen – The Vegan RD

  1. Is milk responsible for male reproductive disorders? – US National Library of Medicine

  1. The Bottom Line on Soy and Breast Cancer Risk – American Cancer Society

  1. Effects of Soymilk Consumption – American Association for Cancer Research

  1. Soy and Manboobs: A Busty Myth? – Mic. the Vegan

  1. Soy Food Intake and Breast Cancer Survival

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